The use of ionic catalysts for olefin polymerization where organometallic transition metal (i.e., metallocene) cations are stabilized in an active polymerization state by compatible, noncoordinating anions is a well-recognized field in the chemical arts. Typically such organometallic transition metal cations are the chemical derivatives of organometallic transition metal compounds having both ancillary ligands which help stabilize the compound in an active electropositive state, and labile ligands at least one of which can be abstracted to render the compound cationic and at least one of which of which is suitable for olefin insertion. Technology for supporting these ionic catalysts is also known.
U.S. Pat. No. 5,427,991 describes the chemical bonding of noncoordinating anionic activators to supports to prepare polyanionic activators that, when used with the metallocene compounds, avoid problems of catalyst desorption experienced when ionic catalysts physically adsorbed on inert supports are utilized in solution or slurry polymerization. The supports are derived from inert monomeric, oligomeric, polymeric or metal oxide support which have been modified to incorporate chemically bound, noncoordinating anions.
The preparation of polyanionic activators from hydrocarbyl compounds entails a number of reactions. A typical reaction for a polymeric core component begins with use of the lithiating agent n-BuLi, or optionally lithiating polymerizable monomers followed by polymerization of monomers into a polymeric segment to produce a polymer or cross-linked polymer having pendant hydrocarbyl lithium groups. These are subsequently treated with the bulky Lewis acid trisperfluorophenylboron (B(pfp).sub.3) and subjected to an ion exchange reaction with dimethylanilinium hydrochloride ([DMAH].sup.+ [Cl].sup.-) which results in a polymer surface having covalently linked activator groups of [DMAH].sup.+ [(pfp).sub.3 BP].sup.-, where P is the polymeric core component.
Another method for attaching a noncoordinating anion activator to the support is described and detailed herein. An aminated polymer is prepared for example by treating a cross-linked polystyrene with a dimethyl amine. The polymer bound amine is then quarternized by ion transfer from [PhNMe.sub.2 H][B(C.sub.6 F.sub.5).sub.4 ]. The resulting support has covalently linked activator groups of [PNMe.sub.2 H][B(C.sub.6 F.sub.5).sub.4 ] where P is again the polymeric core component.
The functionalization of polymer resin beads for use with or preparation of heterogeneous catalytic species is also known. See, e.g., Frechet, J. M. J., Farrall, M. J., "Functionalization of Crosslinked Polystyrene by Chemical Modification", Chemistry and Properties of Crosslinked Polymers, 59-83 (Academic Press, 1977); and Sun, L., Shariati, A., Hsu, J. C. , Bacon, D. W., Studies in Surface Science and Catalysis 1995, 89, 81, and U.S. Pat. No. 4,246,134 which describes polymeric carriers of macroporous copolymers of vinyl and divinyl monomers with specific surface areas of 30 to 70 m.sup.2 /g and the use of such for vinyl monomer polymerization.
In gas phase and slurry polymerization, the use of supported or heterogeneous catalysts increases process efficiencies by assuring that the forming polymeric particles achieve a shape and density that improves reactor operability and ease of handling. However, substituted, bridged indenyl type metallocenes, supported on silica or polymer supports, have long been observed to produce polypropylenes with more regio defects and subsequently shorter meso run lengths as determined by .sup.13 C NMR compared to polymers produced by the respective unsupported metallocenes in solution. These defects result in a decrease in the polymer melting point which is undesirable for many applications. This invention provides a means for minimizing or even eliminating the decreased stereospecificity normally observed when using these metallocenes in supported form. Consequently, the propylene polymers of this invention have fewer defects and higher melting points than those previously obtainable in commercial processes. This achievement represents a significant advantage for polymer producers and their customers.